Compositions and methods of using preactivated unsupported catalyst compositions having a given concentration

ABSTRACT

Preactivated unsupported catalyst compositions methods of using them are disclosed whereby the compositions have a concentration of preactivated catalyst of at least about 0.04 mmol of preactivated catalyst per liter of solution when using aliphatic or alicyclic hydrocarbon solvents, and a concentration of less than about 0.80 mmol/liter when using aromatic or halogen-substituted solvents. In the method, an unsupported catalyst precursor first is contacted with an activator, or co-catalyst, in a suitable reaction medium, and then the resulting mixture is contacted with additional solvent to form a preactivated unsupported olefin polymerization catalyst composition that can be fed to a gas phase polymerization reactor without plugging the catalyst injection nozzle. Combining the unsupported catalyst precursor, the co-catalyst and then adding additional solvent to provide such a composition prevents tube plugging, and provides a catalyst material that has high activity, avoids forming significant amounts of polymer agglomerates, and avoids reactor fouling.

[0001] This is a continuation-in-part of Ser. No. 09/222,638 filed Dec.30, 1998.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to preactivated unsupportedcatalyst compositions and to methods of using them whereby thecompositions have a concentration of preactivated catalyst within therange of from about 0.04 to about 0.1 mmol of preactivated catalyst perliter of solution when using aliphatic or alicyclic hydrocarbonsolvents, and a concentration of less than about 0.80 mmol/liter whenusing aromatic or halogen-substituted solvents. In the method, anunsupported catalyst precursor first is contacted with an activator, orco-catalyst, in a suitable reaction medium, and then the resultingmixture is contacted with additional solvent to form a preactivatedunsupported olefin polymerization catalyst composition that can be fedto a gas phase polymerization reactor without plugging the catalystinjection nozzle. Combining the unsupported catalyst precursor, theco-catalyst and then adding additional solvent to provide a compositionhaving a concentration within the range of from about 0.04 to about 0.1mmol/liter (using aliphatic or alicyclic hydrocarbon solvents) or lessthan about 0.80 mmol/liter (using aromatic or halogenated hydrocarbonsolvents) prevents tube plugging, and provides a catalyst material thathas high activity, avoids forming significant amounts of polymeragglomerates, and avoids reactor fouling.

[0004] 2. Description of Related Art

[0005] Gas phase polymerization of olefin monomers to producepolyolefins is well known in the art. Various polyolefins can beproduced including homopolymers, copolymers and terploymers of α-olefinsand optionally including dienes, aromatic compounds with vinylunsaturation and/or carbon monoxide. A catalyst typically is required toinitiate polymerization of one or more of the α-olefin monomers, and theoptional dienes, etc. Typical catalysts include, but are not limited to,coordinated anionic catalysts, cationic catalysts, free-radicalcatalysts, anionic catalysts and the like. As described more fully,inter alia, in U.S. Pat. Nos. 3,779,712, 3,876,602 and 3,023,203, theseknown catalysts are introduced to the reaction zone as solid particleswhereby the active catalyst material is supported on an inert supporttypically made of alumina, silica and the like. It was generally knownin the art that delivering conventional catalysts to a gas phase reactorthat were unsupported would result in numerous problems in catalystdelivery, as well as undesirable polymer properties.

[0006] Recent developments in the industry, however, have led to thediscovery of a class of unsupported catalysts, some of which aretypically referred to as metallocenes, or single site catalysts.Delivery of liquid, unsupported catalysts to a gas phase reactor wasfirst described in Brady et al., U.S. Pat. No. 5,317,036, the disclosureof which is incorporated herein by reference in its entirety. Bradyrecognized disadvantages of supported catalysts including, inter alia,the presence of ash, or residual support material in the polymer whichincreases the impurity level of the polymer, and a deleterious effect oncatalyst activity because not all of the available surface area of thecatalyst comes into contact with the reactants. Brady further describeda number of advantages attributable to delivering a catalyst to the gasphase reactor in liquid form.

[0007] These advantages included a cost savings since there were nocosts associated with providing the support material, and processing thesupport so as to impregnate the active catalyst thereon. In addition, ahigh catalyst surface area to volume ratio was achieved therebyresulting in improved catalytic activity. Moreover, it was moreefficient since the catalytic solid no longer needed to be separated andprocessed (filtered, washed, dried, etc.), and then handled andtransported.

[0008] Despite these advantages, the solid catalytic material stillneeded to be dissolved in a suitable solvent and delivered to the gasphase reactor in the solvent. Many, if not all, of the single sitemetallocene catalysts which may polymerize olefins, and especiallypropylene isotactically, such as metallocene dichlorides, are difficultto use because they are insoluble in hydrocarbon solvents such asalkanes. Other unsupported catalysts that may polymerize olefins alsoare not readily soluble in hydrocarbon solvents, or require significantamounts of hydrocarbon to dissolve the unsupported catalysts. Solventssuch as toluene and methylene chloride, although capable of solvatingsuch catalysts, are undesirable because they are toxic in nature andleave undesirable residues. Even in these types of solvents, however,solubilities still can be very low, typically less than 21 mmol/l inconcentration at room temperature. In addition, feeding unsupportedcatalysts to a gas phase reactor using large quantities of solvents(hydrocarbon or otherwise) can cause reactor fouling to occur, asdescribed, for example, in U.S. Pat. No. 5,240,894.

[0009] In addition, when a liquid catalyst is employed in gas phasepolymerization, several phenomena can occur. First, the soluble orliquid catalyst tends to deposit on the resin or polymer forming thefluidized bed which in turn leads to accelerated polymerization on thesurface of the particles of the bed. As the coated resin particlesincrease in size, they are exposed to a higher fraction of catalystsolution or spray because of their increased cross-sectional dimensions.If too much catalyst is deposited on the polymer particles, they cangrow so large that they cannot be fluidized thereby causing reactor shutdown.

[0010] Second, using liquid catalyst under conditions of high catalystactivity, e.g., a liquid metallocene catalyst, the initialpolymerization rate is often so high that the newly formed polymer orresin particles can soften or melt, adhering to larger particles in thefluidized bed. This needs to be avoided or minimized to avert reactorshutdown.

[0011] On the other hand, if the polymer particle size is too small,entrainment can occur resulting in fouling of the recycle line,compressor, and cooler and increased static electricity can occurleading to sheeting,—and ultimately, reactor shut down.

[0012] It also was generally thought in the art that introduction ofliquid catalyst to a gas phase polymerization would result in smallparticle sizes, cause undesirable swelling of the polymer or, at thevery least, cause aggregation and agglomeration in the particle bed.This agglomeration would undesirably not fluidize well. Agglomerateswould plug the product discharge valve, coat the walls of the reactorand form sheets, disrupt the flow of solids and gas in the bed, andgenerate large chunks that may extend throughout the reactor. Largeagglomerates also can form at the point of introduction of the liquidcatalyst and plug the catalyst injection nozzle or tube. This may be inpart due to the excess amount of hydrocarbon needed to dissolve theunsupported catalysts. Moreover, carry over of excess liquid occurs,causing an undesirable catalyst coating of the walls of the heatexchanger and other downstream equipment with polymer.

[0013] It is known to contact single site catalysts that are soluble inhydrocarbons with a coactivating cocatalyst solution prior toadministering the catalyst solution to the gas phase reactor, asdescribed, inter alia, U.S. patent application Ser. Nos. 08/781,196 and08/782,499, the disclosures of which are incorporated by referenceherein in their entirety. The amount of hydrocarbon needed to dissolvethe catalyst precursor, however, can be so high to result in an ultimatecatalyst solution whose concentration is low enough to cause coating ofexisting resin particles in the gas phase reactor when the catalystsolution is introduced. This coating phenomenon forms undesirableagglomerates and “chunks” of polymer resin material. This problem isexacerbated when the unsupported catalyst is insoluble in hydrocarbons,or only slightly soluble in hydrocarbon solvent.

[0014] Preactivating an unsupported catalyst precursor with aco-catalyst may be sufficient to enhance the solubility of theunsupported catalyst, and serves to reduce the need to use toxicsolvents, or high quantities of solvent. Plugging of the catalyst feedtube still may occur, however, if the concentration of the unsupportedcatalyst is too high. In addition, if the concentration of theunsupported catalyst is too low, too much liquid may be introduced intothe reactor causing coating of the resin particles, as described above.

SUMMARY OF THE INVENTION

[0015] Thus, there exists a need to develop a mechanism by whichunsupported catalysts can effectively be delivered to a gas phasepolymerization reactor without causing the catalyst feed tube to plug.There also exists a need to develop methods of delivering unsupportedcatalysts to a gas phase reactor without causing polymer agglomeration,and without causing reactor fouling. It is therefore an object of theinvention to provide an unsupported catalyst system and method ofpolymerization that does suffer from the aforementioned problems, andthat satisfies the needs discussed above.

[0016] In accordance with these and other objects of the presentinvention, there is provided a preactivated unsupported olefinpolymerization catalyst composition comprising an unsupported olefinpolymerization catalyst precursor, a co-activator or co-catalyst and asolvent, whereby the concentration of the preactivated unsupportedcatalyst is within the range of from about 0.04 to about 0.1 mmol ofcatalyst per liter of solution when using an aliphatic or alicyclichydrocarbon solvent, and the concentration is less than about 0.80mmol/liter when using an aromatic or halogen-substituted solvent. Inaccordance with an additional object of the present invention, there isprovided a method of making a polymer in a gas phase polymerizationreactor comprising contacting, in the gas phase, an olefin monomer withthe preactivated unsupported olefin polymerization catalyst compositionin liquid form. These and other objects of the invention will be readilyapparent to those skilled in the art upon review of the detaileddescription that follows.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0017] Throughout this description, the expression “liquid form” denotessolutions that contain the preactivated unsupported catalyst whereby theunsupported catalyst is dissolved therein, or is in the form of aslurry. Throughout this description, the term “polyolefin” denoteshomopolymers, copolymers, and terpolymers of α-olefins and mayoptionally contain dienes, aromatic compounds with vinyl unsaturationand/or carbon monoxide.

[0018] It is preferred in the present invention that the unsupportedcatalyst precursor is insoluble in aliphatic or alicyclic hydrocarbons,or only slightly soluble therein. Throughout this description, theexpression “unsupported catalyst precursor” denotes a catalytic solidmaterial that is capable of polymerizing α-olefins (with or without aco-catalyst) without being supported on, inter alia, magnesium chloride,silica, magnesium ethoxide, and the like. Throughout this description,the expression “insoluble in hydrocarbon” or “slightly soluble inhydrocarbon” describes an unsupported catalyst that is either completelyinsoluble in aliphatic or alicyclic hydrocarbon solvents, or has asolubility, at room temperature and pressure, of less than 10 mmol perliter, preferably less than 1 mmol per liter, and most preferably lessthan 0.1 mmol per liter in aliphatic or alicyclic hydrocarbon solvents.

[0019] In addition, the expressions “preactivated unsupported catalyst,”or “preactivated unsupported olefin polymerization catalyst” as they maybe used herein interchangably, denote an unsupported catalyst precursorthat has been contacted with a co-catalyst for a period of timesufficient to generate a catalytic material (“preactivated unsupportedcatalyst”) that, when used to polymerize α-olefins, has an activityabout the same or higher than the activity of the combination ofunsupported catalyst precursor and co-catalyst that were not contactedprior to injection into the reactor, or that were contacted for a periodof time less than about 40 minutes. It is preferred to form apreactivated unsupported olefin polymerization catalyst by contacting anunsupported catalyst precursor and co-catalyst for a period of timesufficient to change the color of the reaction solution. Here, theunsupported catalyst precursors were initially yellow to yellow-orange.After activation by contacting the unsupported catalyst precursor with aco-catalyst, the solution would turn orange-red to deep red. Solutionsthat remained yellow or only partially light orange were not very activeand thus, were not considered to contain a sufficient amount of“preactivated unsupported catalyst.”

[0020] In accordance with preferred embodiments of the presentinvention, the unsupported catalyst precursor and the co-catalyst (or“co-activator”) are first contacted with one another, and thenadditional solvent is added, and the resulting mixture is reacted formore than about 40 minutes, but they can be reacted for as long asdesired. That is, the solution containing the unsupported catalystprecursor and co-catalyst and additional solvent can be storedindefinitely. It is preferred, however, to use the solution containingthe preactivated unsupported catalyst within less than about 3 months ofstorage, more preferably, less than 1 month, and most preferably, lessthan 1 week. In one preferred embodiment of the invention, theunsupported catalyst precursor and co-catalyst are reacted for greaterthan about 50 minutes, the solution then is passed through a filteringmedium to remove any solids, and then the solution is stored for about 1to about 10 days, preferably, from about 1 to about 6 days, and morepreferably from about 1 to about 4 days.

[0021] It is preferred to contact the unsupported catalyst precursor andco-catalyst at temperatures within the range of from about −20 to about80° C., preferably about 0 to about 60° C., and at pressures of up toabout 300 psi, preferably, up to about 20 psi. Because it is preferredto inject the catalyst solution at higher dilution than that obtainedsimply by using the hydrocarbon solvent medium used to dissolve theco-catalyst, additional solvent typically is required. The presentinventors have discovered, however, that it is preferred to contact theunsupported catalyst precursor and co-catalyst with one another first,and then add additional solvent to effectively prevent plugging of thecatalyst injection tube.

[0022] In accordance with the present invention, if an aliphatic oralicyclic hydrocarbon solvent (i.e., methane, ethane, pentane, hexane,heptane, octane, etc.) is used to form the preactivated unsupportedolefin polymerization catalyst composition, then additional hydrocarbonsolvent is added to dilute the concentration of the pre activatedunsupported olefin polymerization catalyst composition. Preferably, thepreactivated unsupported olefin polymerization catalyst is present in aconcentration within the range of from about 0.04 to about 0.1 mmol ofcatalyst per liter of solution. More preferably, the unsupportedpreactivated polymerization catalyst is present in a concentrationwithin the range of from about 0.045 to about 0.07, and most preferablywithin the range of from about 0.048 to about 0.07.

[0023] In accordance with the present invention, if an aromatic orhalogen-substituted solvent is used (i.e., toluene, xylene, methylenechloride) to form the preactivated unsupported olefin polymerizationcatalyst composition, then additional solvent is not needed. Preferably,the preactivated unsupported olefin polymerization catalyst is presentin a concentration within the range of from about 0.01 to about 0.8 mmolof catalyst per liter of solution. More preferably, the unsupportedpreactivated polymerization catalyst is present in a concentrationwithin the range of from about 0.05 to about 0.75, and most preferablywithin the range of from about 0.1 to about 0.70 mmol/liter.

[0024] The present inventors have found that it is advantageous tocontrol the concentration of the preactivated unsupported olefinpolymerization catalyst composition within the ranges noted above. Ingeneral, a more concentrated solution is desirable so that liquidsolvent evaporates rapidly in the reactor, preferably before contactingresin particles, and polymerization begins around the catalyst particlesto form fresh resin particles. While not intending on being bound by anytheory, the inventors believe that if the concentration is too low, thecomposition is sprayed onto existing resin particles causing additionalpolymer to grow on the particles creating larger and larger particles.This ultimately leads to polymer agglomeration, aggregation andplugging, and renders the gas phase polymerization inoperable. If theconcentration of the preactivated unsupported olefin polymerizationcatalyst is too high, however, the solid material may settle out ofsolution or crystallize immediately upon evaporation of minor amounts ofsolvent thereby causing plugging of the catalyst injection tube.

[0025] The inventors found that when an aliphatic or alicyclichydrocarbon solvent is used to prepare the preactivated unsupportedolefin polymerization catalyst composition, the concentration of thepreactivated catalyst should be lower than when an aromatic orhalogen-substituted solvent is used. While not intending on being boundby any theory, the inventors believe that the concentration ofpreactivated catalyst in aromatic or halogenated hydrocarbon solventscan be higher because the solubility of the preactivated catalyst ismuch higher in such solvents. Solvents that improve the solubility ofthe preactivated catalyst therein are preferably used in the invention.As an alternative, means for increasing the solubility in a particularsolvent, e.g., preactivation, also are useful in the present invention.

[0026] Gas phase polymerization reactions typically are carried out influidized bed reactors and stirred or paddle-type reaction systems.While the following discussion will feature fluidized bed systems, wherethe present invention has been found to be preferred and especiallyadvantageous, it is understood that the general concepts relating to theuse of a preactivated unsupported catalyst in liquid form are alsoapplicable to the stirred or paddle-type reaction systems as well. Thoseskilled in the art will appreciate that the present invention is notlimited to any specific type of gas phase reaction system and can becarried out in a stirred or fluidized bed reactor. The invention can becarried out in a single reactor or multiple reactors (two or morereactors in series). In addition to well known conventional gas phasepolymerizations processes, “condensed mode”, including the so-called“induced condensed mode”, and “liquid monomer” operation of a gas phasepolymerization can be employed.

[0027] A conventional fluidized bed process for producing resins ispracticed by passing a gaseous stream containing one or more monomerscontinuously through a fluidized bed reactor under reactive conditionsin the presence of a polymerization catalyst. Product is withdrawn fromthe reactor. A gaseous stream of unreacted monomer is withdrawn from thereactor continuously and recycled into the reactor along with make-upmonomer added to the recycle stream. Condensed mode polymerizations aredisclosed in U.S. Pat. Nos. 4,543,399; 4,588,790; 5,352,749; and5,462,999. Condensing mode processes are employed to achieve highercooling capacities and, hence, higher reactor productivity. In thesepolymerizations a recycle stream, or a portion thereof, can be cooled toa temperature below the dew point in a fluidized bed polymerizationprocess, resulting in condensing all or a portion of the recycle stream.The recycle stream is returned to the reactor. The dew point of therecycle stream can be increased by increasing the operating pressure ofthe reaction/recycle system and/or increasing the percentage ofcondensable fluids and decreasing the percentage of non-condensablegases in the recycle stream. The condensable fluid may be inert to thecatalyst, reactants and the polymer product produced; it may alsoinclude monomers and comonomers. The condensing fluid can be introducedinto the reaction/recycle system at any point in the system. Condensablefluids include saturated or unsaturated hydrocarbons. In additioncondensable fluids of the polymerization process itself othercondensable fluids, inert to the polymerization can be introduce to“induce” condensing mode operation. Examples of suitable condensablefluids may be selected from liquid saturated hydrocarbons containing 2to 8 carbon atoms (e.g., propane, n-butane, isobutane, n-pentane,isopentane, neopentane, n-hexane, isohexane, and other saturated C₆hydrocarbons, n-heptane, n-octane and other saturated C₇ and C₈hydrocarbons, and mixtures thereof). Condensable fluids may also includepolymerizable condensable comonomers such as olefins, alpha-olefins,diolefins, diolefins containing at least one alpha olefin, and mixturesthereof. In condensing mode, it desirable that the liquid entering thefluidized bed be dispersed and vaporized quickly.

[0028] Liquid monomer polymerization mode is disclosed, in U.S. Pat. No.5,453,471, U.S. Ser. No. 510,375, PCT 95/09826 (US) and PCT 95/09827(US). When operating in the liquid monomer mode, liquid can be presentthroughout the entire polymer bed provided that the liquid monomerpresent in the bed is adsorbed on or absorbed in solid particulatematter present in the bed, such as polymer being produced orfluidization aids (e.g., carbon black) present in the bed, so long asthere is no substantial amount of free liquid monomer present more thana short distance above the point of entry into the polymerization zone.Liquid mode makes it possible to produce polymers in a gas phase reactorusing monomers having condensation temperatures much higher than thetemperatures at which conventional polyolefins are produced. In general,liquid monomer processes are conducted in a stirred bed or gas fluidizedbed reaction vessel having a polymerization zone containing a bed ofgrowing polymer particles. The process comprises continuouslyintroducing a stream of one or more monomers and optionally one or moreinert gases or liquids into the polymerization zone; continuously orintermittently introducing a polymerization catalyst into thepolymerization zone; continuously or intermittently withdrawing polymerproduct from the polymerization zone; and continuously withdrawingunreacted gases from the zone; compressing and cooling the gases whilemaintaining the temperature within the zone below the dew point of atleast one monomer present in the zone. If there is only one monomerpresent in the gas-liquid stream, there is also present at least oneinert gas. Typically, the temperature within the zone and the velocityof gases passing through the zone are such that essentially no liquid ispresent in the polymerization zone that is not adsorbed on or absorbedin solid particulate matter.

[0029] Fluidized bed gas phase reaction systems are described, forexample, in Brady, et al., U.S. Pat. No. 5,317,036. As describedtherein, a conventional fluidized bed process for producing resins isconducted by passing a gaseous stream containing one or more monomerscontinuously through a fluidized bed reactor under reactive conditionsand in the presence of catalyst at a velocity sufficient to maintain thebed of solid particles in a suspended condition. The gaseous streamcontaining unreacted gaseous monomer is withdrawn from the reactorcontinuously, compressed, cooled, optionally condensed, and recycledinto the reactor. Product is withdrawn from the reactor and make-upmonomer is added to the recycle stream.

[0030] The reaction zone of the gas phase polymerization fluidized bedreactor typically comprises a bed of growing polymer particles, formedpolymer particles and a minor amount of catalyst all fluidized by thecontinuous flow of polymerizable and modifying gaseous components,including inerts, in the form of make-up feed and recycle fluidthroughout the reaction zone. To maintain a viable fluidized bed, thesuperficial gas velocity through the bed typically must exceed theminimum flow required for fluidization which is typically from about 0.1to about 0.8 ft/sec. Preferably, the superficial gas velocity is atleast 0.2 ft/sec above the minimum flow for fluidization, or from about0.3 to about 0.7 ft/sec. Ordinarily, the superficial gas velocity willnot exceed 5.0 ft/sec and is usually no more than about 2.5 ft/sec.

[0031] During start up, the reactor generally is charged with a bed ofparticulate polymer particles before initiation of gas flow. Theseparticles help to prevent the formation of localized ‘hot spots’ whencatalyst feed is initiated. They may be the same as the polymer to beformed or different. When different, they are withdrawn with the desirednewly formed polymer particles as the first product. Eventually, afluidized bed consisting of desired polymer particles supplants thestart-up bed.

[0032] Fluidization typically can be achieved by utilizing a high rateof fluid recycled to and through the bed, usually on the order of about50 times the rate of feed or make-up fluid. This high rate of recycleprovides the requisite superficial gas velocity necessary to maintainthe fluidized bed. The fluidized bed has the general appearance of adense mass of individually moving particles as created by thepercolation of gas through the bed. The pressure drop through the bed isequal to or slightly greater than the weight of the bed divided by thecross-sectional area.

[0033] Unreacted gas flowing through the fluidized bed generally ispassed upwardly into a velocity reduction zone above the bed where aportion of the entrained particles drop back onto the bed therebyreducing solid particle carryover. All or only a portion of theunreacted gas then can be recycled to the reactor by compressing andcondensing the gas, and then introducing the recycle stream to thereactor.

[0034] The monomers that can be used for preparing the polymers of theinvention are an olefin monomer capable of being polymerized, andpreferably are those olefin monomers having from two to twelve carbonatoms, more preferably those olefin monomers having two to six carbonatoms. Preferred monomers are ethylene, propylene, butene-1,pentene-1,4-methylpentene-1 and hexene-1.

[0035] The polymers of the present invention also can include dienes,aromatic compounds with vinyl unsaturation and/or carbon monoxide.Preferred dienes are non-conjugated or conjugated diene monomers thatare straight chain, branched chain or cyclic hydrocarbon dienes havingfrom about 5 to about 15 carbon atoms. Particularly preferred dienesinclude 1,4-hexadiene and 5-ethylidene-2-norbornene. Preferred aromaticcompounds with vinyl unsaturation that also may be polymerized includestyrene and substituted styrene. Particularly preferred polymers thatcan be made in accordance with the present invention include ethylenehomopolymers and ethylene copolymers employing one or more C₃-C₁₂ alphaolefins; propylene homopolymers and propylene copolymers employing oneor more C₄-C₁₂ alpha olefins; polyisoprene; polystyrene; polybutadiene;polymers of butadiene copolymerized with styrene; polymers of butadienecopolymerized with acrylonitrile; polymers of isobutylene copolymerizedwith isoprene; ethylene propylene rubbers and ethylene propylene dienerubbers; polychloroprene, and the like.

[0036] The process of the present invention may employ any suitableadditive necessary to effect, assist or otherwise complement thepolymerization. For example, the process of the invention can optionallyemploy inert particulate materials as fluidization aids. These inertparticulate materials can include carbon black, silica, talc, and clays,as well as inert polymeric materials. Carbon black has a primaryparticle size of about 10 to about 100 nanometers, an average size ofaggregate of about 0.1 to about 10 microns, and a specific surface areaof about 30 to about 1,500 m²/gm. Silica has a primary particle size ofabout 5 to about 50 nanometers, an average size of aggregate of about0.1 to about 10 microns, and a specific surface area of about 50 to 500m²/gm. Clay, talc, and polymeric materials have an average particle sizeof about 0.01 to about 10 microns and a specific surface area of about 3to 30 m²/gm. These inert particulate materials are employed in amountsranging about 0.3 to about 80%, preferably about 5 to about 50%, basedon the weight of the final product. They are especially useful for thepolymerization of sticky polymers as disclosed in U.S. Pat. Nos.4,994,534 and 5,304,588.

[0037] Chain transfer agents, promoters, scavenging agents and otheradditives can be, and often are, employed in the polymerization processof the invention. Chain transfer agents are often used to controlpolymer molecular weight. Examples of these compounds are hydrogen andmetal alkyls of the general formula M³R⁵g, where M³ is a Group IA, IIAor IIIA metal, R⁵ is an alkyl or aryl, and g is 1, 2, or 3. Preferably,a zinc alkyl is employed; and, of these, diethyl zinc is most preferred.Typical promoters include halogenated hydrocarbons such as CHCl₃, CFCl₃,CH₃CCl₃, CF₂ClCCl₃, and ethyltrichloroacetate. Such promoters are wellknown to those skilled in the art and are disclosed in, for example,U.S. Pat. No. 4,988,783. Other organometallic compounds such asscavenging agents for poisons may also be employed to increase catalystactivity. Examples of these compounds include metal alkyls, such asaluminum alkyls, most preferably triusobutylaluminum. Some compounds maybe used to neutralize static in the fluidized-bed reactor, others knownas drivers rather than antistatic agents, may consistently force thestatic to from positive to negative or from negative to positive. Theuse of these additives is well within the skill of those skilled in theart. These additives may be added to the reaction zone separately orindependently from the liquid catalyst if they are solids, or as part ofthe catalyst provided they do not interfere with the catalyst delivery.To be part of the catalyst solution, the additives should be liquids orcapable of being dissolved in the catalyst solution.

[0038] Exemplary catalysts useful in the present invention are anyunsupported catalyst useful for preparing polyolefins from olefinmonomers, and preferably, unsupported catalysts that are insoluble oronly slightly soluble in hydrocarbon solvents. A single catalyst may beused, or a mixture of catalysts may be employed if desired. Thesecatalysts typically are used with cocatalysts and promoters well knownin the art. Examples of suitable catalysts include:

[0039] A. Ziegler-Natta catalysts, including titanium based catalystssuch as those described in U.S. Pat. Nos. 4,376,062 and 4,379,758, thedisclosures of which are incorporated by reference herein in theirentirety. Ziegler-Natta catalysts are well known in the art, andtypically are magnesium/titanium/electron donor complexes used inconjunction with an organoaluminum cocatalyst.

[0040] B. Chromium based catalysts such as those described in U.S. Pat.Nos. 3,709,853; 3,709,954; and 4,077,904, the disclosure of which isincorporated herein in its entirety.

[0041] C. Vanadium based catalysts such as vanadium oxychloride andvanadium acetylacetonate, such as described in U.S. Pat. No. 5,317,036,the disclosure of which is incorporated by reference herein in itsentirety.

[0042] D. Metallocene catalysts described in, for example, U.S. Pat.Nos. 4,361,497 and 4,404,344 and in WO94/28219, the disclosures of whichare incorporated by reference herein in their entirety.

[0043] E. Cationic forms of metal halides, such as aluminum trihalides.

[0044] F. Cobalt catalysts and mixtures thereof such as those describedin U.S. Pat. Nos. 4,472,559 and 4,182,814, the disclosures of which areincorporated by reference herein in their entirety.

[0045] G. Nickel catalysts and mixtures thereof such as those describedin U.S. Pat. Nos. 4,155,880 and 4,102,817, the disclosures of which areincorporated by reference herein in their entirety.

[0046] H. Rare Earth metal catalysts, i.e., those containing a metalhaving an atomic number in the Periodic Table of 57 to 103, such ascompounds of cerium, lanthanum, praseodymium, gadolinium and neodymium.Especially useful are carboxylates, alcoholates, acetylacetonates,halides (including ether and alcohol complexes of neodymiumtrichloride), and allyl derivatives of such metals. Neodymium compounds,particularly neodymium neodecanoate, octanoate, and versatate, are themost preferred rare earth metal catalysts. Rare earth catalysts are usedto produce polymers polymerized using butadiene or isoprene.

[0047] Preferred among these different catalyst systems are catalystcompositions comprising a mixture of at least one metallocene catalystand an activating cocatalyst, whereby the resulting mixture is solublein hydrocarbon solvent. The metallocene catalyst first is added to theactivating co-catalyst solution (the co-catalyst typically beingdissolved in a hydrocarbon solvent), and then additional solvent isadded to further dilute the preactivated unsupported catalyst mixture.The practice of this invention is not limited to any particular class orkind of metallocene catalyst. Accordingly, the catalyst composition maycomprise any unsupported metallocene catalyst useful in slurry,solution, bulk, or gas phase olefin polymerization. One or more than onemetallocene catalyst may be employed. For example, as described in U.S.Pat. No. 4,530,914, the disclosure of which is incorporated by referenceherein in its entirety, at least two metallocene catalysts may be usedin a single catalyst composition to achieve a broadened molecular weightdistribution polymer product.

[0048] Metallocene catalysts typically are organometallic coordinationcomplexes of one or more π-bonded moieties in association with a metalatom from Groups IIIB to VIII or the rare earth metals of the PeriodicTable.

[0049] Bridged and unbridged mono-, bis-, and tris-cycloalkadienyl/metalcompounds are the most common metallocene catalysts, and generally areof the formula:

(L)_(y)R¹ _(z)(L′)MX_((x−y−1))  (I)

[0050] wherein M is a metal from groups IIIB to VIII of the PeriodicTable; L and L′ are the same or different and are π-bonded ligandscoordinated to M, preferably cycloalkadienyl groups such ascyclopentadienyl, indenyl, or fluorenyl groups optionally substitutedwith one or more hydrocarbyl groups containing 1 to 20 carbon atoms; R¹is a C₁-C₄ substituted or unsubstituted alkylene radical, a dialkyl ordiaryl germanium or silicon, or an alkyl or aryl phosphine or amineradical bridging L and L′; each X is independently hydrogen, an aryl,alkyl, alkenyl, alkylaryl, or arylalkyl radical having 1-20 carbonatoms, a hydrocarboxy radical having 1-20 carbon atoms, a halogen,R²CO₂—, or R² ₂NCO₂—, wherein each R² is a hydrocarbyl group containing1 to about 20 carbon atoms; n and m are each 0, 1, 2, 3, or 4; y is 0,1, or 2; x is 1, 2, 3, or 4 depending upon the valence state of M; z is0 or 1 and is 0 when y is 0; and x-y □ is 1.

[0051] Illustrative but non-limiting examples of metallocene catalystsrepresented by formula II are dialkyl metallocenes such asbis(cyclopentadienyl) titanium dimethyl, bis(cyclopentadienyl) titaniumdiphenyl, bis(cyclopentadienyl) zirconium dimethyl,bis(cyclopenta-dienyl) zirconium diphenyl, bis(cyclopentadienyl) hafniummethyl and diphenyl, bis(cyclopentadienyl) titanium dineopentyl,bis(cyclopentadienyl) zirconium di-neopentyl, bis(cyclopentadienyl)titanium dibenzyl, bis(cyclopentadienyl) zirconium dibenzyl,bis(cyclopentadienyl) vanadium dimethyl; mono alkyl metallocenes such asbis(cyclopentadienyl) titanium methyl chloride, bis(cyclopentadienyl)titanium ethyl chloride, bis(cyclopentadienyl) titanium phenyl chloride,bis(cyclopentadienyl) zirconium methyl chloride, bis(cyclopentadienyl)zirconium ethyl chloride, bis(cyclopentadienyl) zirconium phenylchloride, bis(cyclopentadienyl) titanium methyl bromide; trialkylmetallocenes such as cyclopentadienyl titanium trimethyl,cyclopentadienyl zirconium triphenyl, and cyclopentadienyl zirconiumtrineopentyl, cyclopentadienyl zirconium trimethyl, cyclopentadienylhafnium triphenyl, cyclopentadienyl hafnium trineopentyl, andcyclopentadienyl hafnium trimethyl; monocyclopentadienyl titanocenessuch as, pentamethylcyclopentadienyl titanium trichloride,pentaethylcyclopentadienyl titanium trichloride;bis(pentamethylcyclopentadienyl) titanium diphenyl, the carbenerepresented by the formula bis(cyclopentadienyl)titanium=CH₂ andderivatives of this reagent; substituted bis(cyclopentadienyl)titanium(IV) compounds such as: bis(indenyl)titanium diphenyl or dichloride,bis(methylcyclopentadienyl)titanium diphenyl or dihalide; dialkyl,trialkyl, tetraalkyl and pentaalkyl cyclopentadienyl titanium compoundssuch as bis(1,2-dimethylcyclopentadienyl) titanium diphenyl ordichloride, bis(1,2-diethylcyclopentadienyl) titanium diphenyl ordichloride; silicon, phosphine, amine or carbon bridged cyclopentadienecomplexes, such as dimethyl silyldicyclopentadienyl titanium diphenyl ordichloride, methyl phosphine dicyclopentadienyl titanium diphenyl ordichloride, methylenedicy clopentadienyl titanium diphenyl or dichlorideand other dihalide complexes, and the like; as well as bridgedmetallocene compounds such as isopropyl (cyclopentadienyl)(fluorenyl)zirconium dichloride, isopropyl (cyclopentadienyl)(octahydrofluorenyl)zirconium dichloride, diphenylmethylene (cyclopentadienyl)(fluorenyl)zirconium dichloride, diisopropylmethylene(cyclopentadienyl)(fluorenyl)-zirconium dichloride, diisobutylmethylene(cyclopentadienyl)(fluorenyl) zirconium dichloride, ditertbutylmethylene(cyclopentadienyl) (fluorenyl) zirconium dichloride, cyclohexylidene(cyclopentadienyl)(fluorenyl) zirconium dichloride, diisopropylmethylene(2,5-dimethylcyclopentadienyl) (fluorenyl) zirconium dichloride,isopropyl (cyclopentadienyl)(fluorenyl) hafnium dichloride,diphenylmethylene (cyclopentadienyl) (fluorenyl) hafnium dichloride,diisopropylmethylene (cyclopentadienyl) (fluorenyl) hafnium dichloride,diisobutylmethylene (cyclopentadienyl) (fluorenyl) hafnium dichloride,ditertbutylmethylene (cyclopentadienyl) (fluorenyl) hafnium dichloride,cyclohexylidene (cyclopentadienyl) (fluorenyl) hafnium dichloride,diisopropylmethylene (2,5-dimethylcyclopentadienyl) (fluorenyl)-hafniumdichloride, isopropyl (cyclopentadienyl) (fluorenyl) titaniumdichloride, diphenylmethylene (cyclopentadienyl) (fluorenyl) titaniumdichloride, diisopropylmethylene (cyclopentadienyl) (fluorenyl) titaniumdichloride, diisobutylmethylene (cyclopentadienyl) (fluorenyl) titaniumdichloride, ditertbutylmethylene (cyclopentadienyl) (fluorenyl) titaniumdichloride, cyclohexylidene (cyclopentadienyl) (fluorenyl) titaniumdichloride, diisopropylmethylene (2,5 dimethylcyclopentadienylfluorenyl) titanium dichloride, racemic-ethylene bis (1-indenyl)zirconium (IV) dichloride, racemic-ethylene bis(4,5,6,7-tetrahydro-1-indenyl) zirconium (IV) dichloride,racemic-dimethylsilyl bis (1-indenyl) zirconium (IV) dichloride,racemic-dimethylsilyl bis (4,5,6,7-tetrahydro-1-indenyl) zirconium (IV)dichloride, racemic-1,1,2,2-tetramethylsilanylene bis (1-indenyl)zirconium (IV) dichloride, racemic-1,1,2,2-tetramethylsilanylene bis(4,5,6,7-tetrahydro-1-indenyl) zirconium (IV) dichloride, ethylidene(1-indenyl tetramethylcyclopentadienyl) zirconium (IV) dichloride,racemic-dimethylsilyl bis (2-methyl-4-t-butyl-1-cyclopentadienyl)zirconium (IV) dichloride, racemic-ethylene bis (1-indenyl) hafnium (IV)dichloride, racemic-ethylene bis (4,5,6,7-tetrahydro-1-indenyl) hafnium(IV) dichloride, racemic-dimethylsilyl bis (1-indenyl) hafnium (IV)dichloride, racemic-dimethylsilyl bis (4,5,6,7-tetrahydro-1-indenyl)hafnium (IV) dichloride, racemic-1,1,2,2-tetramethylsilanylene bis(1-indenyl) hafnium (IV) dichloride,racemic-1,1,2,2-tetramethylsilanylene bis (4,5,6,7-tetrahydro-1-indenyl)hafnium (IV), dichloride, ethylidene(1-indenyl-2,3,4,5-tetramethyl-1-cyclopentadienyl) hafnium (IV)dichloride, racemic-ethylene bis (1-indenyl) titanium (IV) dichloride,racemic-ethylene bis (4,5,6,7-tetrahydro-1-indenyl) titanium (IV)dichloride, racemic-dimethylsilyl bis (1-indenyl) titanium (IV)dichloride, racemic-dimethylsilyl bis (4,5,6,7-tetrahydro-1-indenyl)titanium (IV) dichloride, racemic-1,1,2,2-tetramethylsilanylene bis(1-indenyl) titanium (IV) dichlorideracemic-1,1,2,2-tetramethylsilanylene bis (4,5,6,7-tetrahydro-1-indenyl)titanium (IV) dichloride, and ethylidene(1-indenyl-2,3,4,5-tetramethyl-1-cyclopentadienyl) titanium IV)dichloride.

[0052] Particularly preferred metallocene catalysts have one of thefollowing formulas (III or IV):

[0053] wherein:

[0054] M is a metal from groups IIIB to VIII, preferably Zr or Hf;

[0055] L is a substituted or unsubstituted, □π-bonded ligand coordinatedto M, preferably a substituted cycloalkadienyl ligand;

[0056] each Q is independently selected from the group consisting of—O—, —NR³—, —CR³ ₂— and —S—, preferably oxygen;

[0057] Y is either C or S, preferably carbon;

[0058] Z is selected from the group consisting of —OR³, —NR³ ₂, —CR³ ₃,—SR³, —SiR³ ₃, —PR³ ₂, and —H, with the proviso that when Q is —NR³—then Z is selected from the group consisting of —OR³, —NR³ ₂, —SR³,—SiR³ ₃, —PR³ ₂, and —H, preferably Z is selected from the groupconsisting of —OR³, —CR³ ₃, and —NR³ ₂;

[0059] n is 1 or 2;

[0060] A is a univalent anionic group when n is 2 or A is a divalentanionic group when n is 1, preferably A is a carbamate, carboxylate orother heteroallyl moiety described by Q, Y and Z combination; and

[0061] each R³ is independently a group containing carbon, silicon,nitrogen, oxygen, and/or phosphorus and one or more R³ groups may beattached to the L substituent, preferably R³ is a hydrocarbon groupcontaining from 1 to 20 carbon atoms, most preferably an alkyl,cycloalkyl or an aryl group;

[0062] T is a bridging group selected from the group consisting ofalkylene or arylene groups containing from 1 to 10 carbon atomsoptionally substituted with carbon or heteroatoms, germanium, siliconeand alkyl phosphine; and

[0063] m is 1 to 7, preferably 2 to 6, most preferably 2 or 3.

[0064] The supportive substituent formed by Q, Y and Z is a unichargedpolydentate ligand exerting electronic effects due to its highpolarizability, similar to the cyclopentadienyl group. In the mostpreferred embodiments of this invention, the disubstituted carbamates offormula (IV),

[0065] and the carboxylates of formula (V)

[0066] are employed.

[0067] Examples of metallocene catalysts according to formulas II andIII include indenyl zirconium tris(diethylcarbamate), indenyl zirconiumtris(pivalate), indenyl zirconium tris(p-toluate), indenyl zirconiumtris(benzoate), (1-methylindenyl) zirconium tris(pivalate),(2-methylindenyl) zirconium tris(diethylcarbamate),(methylcyclopentadienyl) zirconium tris(pivalate), cyclopentadienyltris(pivalate), and (pentamethylcyclopentadienyl) zirconiumtris(benzoate). Preferred examples of these metallocene catalystsinclude indenyl zirconium tris(diethylcarbamate ) and indenyl zirconiumtris(pivalate).

[0068] Another type of metallocene catalyst that can be used inaccordance with the invention is a constrained geometry catalyst of theformula (VI):

[0069] wherein:

[0070] M is a metal of Group IIIB to VIII of the Periodic Table of theElements:

[0071] Cp is a cyclopentadienyl or substituted cyclopentadienyl groupbound in an η⁵ bonded mode to M;

[0072] Z′ is a moiety comprising boron, or a member of Group IVB of thePeriodic Table of the Elements and optionally sulfur or oxygen, themoiety having up to 20 non-hydrogen atoms, and optionally Cp and Z′together form a fused ring system;

[0073] X′ is an anionic ligand group or a neutral Lewis base ligandgroup having up to 30 non-hydrogen atoms;

[0074] a is 0, 1, 2, 3 or 4 depending on the valance of M; and

[0075] Y′ is an anionic or non-anionic ligand group bonded to Z′ and Mcomprising is nitrogen, phosphorus, oxygen or sulfur having up to 20non-hydrogen atoms, and optionally Y′ and Z′ together form a fused ringsystem.

[0076] Constrained geometry catalysts are well known to those skilled inthe art and are disclosed in, for example, U.S. Pat. Nos. 5,026,798 and5,055,438 and published European Application No. 0 416 815 A2, thedisclosures of which are incorporated by reference herein in theirentirety.

[0077] Illustrative but non-limiting examples of substituents Z′, Cp,Y′, X′ and M in formula V are: Z^(′) Cp Y^(′) X^(′) M dimethyl-cyclopenta- t-butylamido chloride titanium silyl dienyl methyl-fluorenyl phenylamido methyl zirconium phenylsilyl diphenyl- indenylcyclohexylamido hafnium silyl tetramethyl- oxo ethylene ethylenetetramethyl- cyclopenta- dienyl diphenyl- methylene

[0078] Another preferred group of metallocene catalysts useful in thepresent invention are those having the following formula.

(L)₂R¹MX_((z−2))  (VII)

[0079] wherein M is a metal from groups III to VIII or a rare earthmetal of the Periodic Table; L is i-bonded substituted indenyl ligandcoordinated to M; R¹ is a bridging group selected from the groupconsisting of C₁-C₄ substituted or unsubstituted alkylene radicals,dialkyl or diaryl germanium or silicon groups, and alkyl or arylphosphine or amine radicals; each X is independently hydrogen, an aryl,alkyl, alkenyl, alkylaryl, or arylalkyl radical having 1-20 carbonatoms, a hydrocarboxy radical having 1-20 carbon atoms, a halogen, NR²₂—, R²CO₂—, or R² ₂NCO₂—, wherein each R² is a hydrocarbyl groupcontaining 1 to about 20 carbon atoms; and z is the valence state of M.

[0080] Illustrative, but non-limiting, examples of this group ofmetallocenes include bridged dialkyl indenyl metallocenes [e.g.,(indenyl)₂M(CH₃)₂, (indenyl)₂M(C₆H₅)₂, (indenyl)₂M di-neopentyl,(indenyl)₂M di-benzyl]; bridged mono alkyl bisindenyl metallocenes,[e.g., (indenyl)₂M(CH₃)Cl, (indenyl)₂M neopentyl Cl, (indenyl)₂MC₆H₅Cl],indenyl metal di-halide complexes [e.g., indenyl₂MCl₂,tetra-methylindenyl₂MCl₂, tetra-ethylindenyl₂MCl₂, bis(2,4dimethyl-indenyl)MCl₂]; bisfluorenyl structures [e.g., bisfluorenylMCl₂,bis-nona methyl fluorenylMCl₂, bis-1-methyl fluorenylMCl₂]; with thefollowing bridging groups (i.e., R in the above formula I): Me₂Si,Et₂Si, Ph₂Si, MePhSi, MeEtSi, EtPhSi, Me₂Ge, Et₂Ge, Ph₂Ge, MePhiGe,MeEtGe, MeCH, Me₂C, Et₂C, Ph₂C, MePhC, MeEtC, EtPhC, iPr₂C, t-BU₂C,ethylene, tetramethylethylene, diphenyl ethylene, methyl ethylene,propylene, methylamine, butylene, and methyl phosphine.

[0081] Particularly preferred for use herein are compounds selected fromracemic-dimethylsilylbis(2-methyl-1-indenyl) zirconium dichloride(“SIZR2”), racemic-dimethylsilylbis(2-methyl-47-(1-naphthyl)indenyl)zirconium dichloride (“SIZR4N”) and racemic-dimethylsilylbis(2-methyl-4-phenyl-1-indenyl) zirconium dichloride (“SIZR4P”).

[0082] The invention is also useful with another class of single sitecatalyst precursors, di(imine) metal complexes, as described in PCTApplication No. WO 96/23010. Such di(imine) metal complexes aretransition metal complexes of bidentate ligands selected from the groupconsisting of:

[0083] wherein said transition metal is selected from the groupconsisting of Ti, Zr, Sc, V, Cr, a rare earth metal, Fe, Co, Ni, and Pd;

[0084] R² and R⁵ are each independently hydrocarbyl or substitutedhydrocarbyl, provided that the carbon atom bound to the imino nitrogenatom has at least two carbon atoms bound to it;

[0085] R³ and R⁴ are each independently hydrogen, hydrocarbyl,substituted hydrocarbyl, or R³ and R⁴ taken together are hydrocarbyleneor substituted hydrocarbylene to form a carbocyclic ring;

[0086] R⁴⁴ is hydrocarbyl or substituted hydrocarbyl, and R²⁸ ishydrogen, hydrocarbyl or substituted hydrocarbyl or R⁴⁴ and R²⁸ takentogether form a ring;

[0087] R⁴⁵ is hydrocarbyl or substituted hydrocarbyl, and R²⁹ ishydrogen, substituted hydrocarbyl or hydrocarbyl, or R⁴⁵ and R²⁹ takentogether form a ring;

[0088] each R³⁰ is independently hydrogen, substituted hydrocarbyl orhydrocarbyl, or two of R³⁰ taken together form a ring;

[0089] each R³¹ is independently hydrogen, hydrocarbyl or substitutedhydrocarbyl;

[0090] R⁴⁶ and R⁴⁷ are each independently hydrocarbyl or substitutedhydrocarbyl, provided that the carbon atom bound to the imino nitrogenatom has at least two carbon atoms bound to it;

[0091] R⁴⁸ and R⁴⁹ are each independently hydrogen, hydrocarbyl, orsubstituted hydrocarbyl;

[0092] R²⁰ and R²³ are independently hydrocarbyl or substitutedhydrocarbyl;

[0093] R²¹ and R²² are independently hydrogen, hydrocarbyl orsubstituted hydrocarbyl; and

[0094] n is 2 or 3;

[0095] and provided that:

[0096] said transition metal also has bonded to it a ligand that may bedisplaced by or added to the olefin monomer being polymerized; and

[0097] when the transition metal is Pd, said bidentate ligand is (IX),(X) or (XI).

[0098] The activating cocatalyst typically is capable of activating themetallocene catalyst. Preferably, the activating cocatalyst is one ofthe following: (a) branched or cyclic oligomericpoly(hydrocarbyl-aluminum oxide)s which contain repeating units of thegeneral formula —(Al(R*)O)—, where R* is hydrogen, an alkyl radicalcontaining from 1 to about 12 carbon atoms, or an aryl radical such as asubstituted or unsubstituted phenyl or naphthyl group; (b) ionic saltsof the general formula [A⁺][BR**₄—], where A⁺ is a cationic Lewis orBronsted acid capable of abstracting an alkyl, halogen, or hydrogen fromthe metallocene catalysts, B is boron, and R** is a substituted aromatichydrocarbon, preferably a perfluorophenyl radical; and (c) boron alkylsof the general formula BR**₃, where R** is as defined above.

[0099] Preferably, the activating cocatalyst is an aluminoxane such asmethylaluminoxane (MAO) or modified methylaluminoxane (MMAO), or a boronalkyl. Aluminoxanes are preferred and their method of preparation iswell known in the art. Aluminoxanes may be in the form of oligomericlinear alkyl aluminoxanes represented by the formula (XII):

[0100] or oligomeric cyclic alkyl aluminoxanes of the formula (XIII):

[0101] wherein s is 1-40, preferably 10-20; p is 3-40, preferably 3-20;and R*** is an alkyl group containing 1 to 12 carbon atoms, preferablymethyl or an aryl radical such as a substituted or unsubstituted phenylor naphthyl radical. In the case of MAO, R*** is methyl, whereas inMMAO, R*** is a mixture of methyl and C2 to C12 alkyl groups whereinmethyl comprises about 20 to 80 percent by weight of the R*** group.

[0102] The amount of activating cocatalyst and metallocene catalystusefully employed in preparation of the catalyst composition can varyover a wide range. When the cocatalyst is a branched or cyclicoligomeric poly(hydrocarbylaluminum oxide), the mole ratio of aluminumatoms contained in the poly(hydrocarbylaluminum oxide) to metal atomscontained in the metallocene catalyst is generally in the range of fromabout 2:1 to about 100,000:1, preferably in the range of from about 10:1to about 10,000:1, and most preferably in the range of from about 50:1to about 2,000:1. When the cocatalyst is an ionic salt of the formula[A⁺][BR*₄—] or a boron alkyl of the formula BR*₃, the mole ratio ofboron atoms contained in the ionic salt or the boron alkyl to metalatoms contained in the metallocene catalyst is generally in the range offrom about 0.5:1 to about 10:1, preferably in the range of from about1:1 to about 5:1.

[0103] The liquid preactivated unsupported catalyst can be composed ofone or more metal compounds (i.e., unsupported catalyst) in combinationwith one or more co-catalysts. Alternatively, a portion of theco-catalyst can be fed separately from the metal compound(s) to thereactor. Promoters associated with any particularly polymerization areusually added to the reactor separately from the co-catalyst and/ormetal compound(s).

[0104] If the metal compound and/or the co-catalyst occurs naturally inliquid form, it can be introduced “neat” into the reactor. More likely,the liquid catalyst is introduced into the reactor as a solution (singlephase, or “true solution” using a solvent to dissolve the mixture of themetal compound and the co-catalyst), an emulsion (partially dissolvingthe catalyst components in a solvent), suspension, dispersion, or slurry(each having at least two phases). Preferably, the liquid catalystemployed is a solution or an emulsion, most preferably a solution. Asused herein, “liquid catalyst” or “liquid form” includes neat, solution,emulsion, and dispersions of the transition metal or rare earth metalcomponent(s) of the catalyst and/or co-catalyst.

[0105] The solvents that can be utilized to form solutions of themixture of the preactivated unsupported olefin polymerization catalystprecursor compounds and co-catalyst (i.e., the preactivated unsupportedcatalyst) are inert solvents, preferably non-functional andnon-coordinating hydrocarbon solvents, and may include aliphatichydrocarbons such as butane, isobutane, ethane, propane, pentane,isopentane, hexane, heptane, octane, decane, dodecane, hexadecane,octadecane, and the like; alicyclic hydrocarbons such as cyclopentane,methylcyclopentane, cyclohexane, cycloctane, norbornane,ethylcyclohexane and the like; aromatic hydrocarbons such as benzene,toluene, ethylbenzene, propylbenzene, butylbenzene, xylene,tetrahydrofuran and the like; and petroleum fractions such as gasoline,kerosene, light oils, and the like. Likewise, halogenated solvents suchas methylene chloride, chlorobenzene, and the like may also be utilized.The use of the term “inert” in this context is meant that the materialbeing referred to is non-deactivating in the polymerization reactionzone under the conditions of gas phase polymerization and isnon-deactivating with the catalyst in or out of the reaction zone. Theuse of the expression “non-functional” or “non-coordinating” denotessolvents that do not contain groups such as strong polar groups whichcan deactivate the active catalyst metal sites.

[0106] Although aromatic and halogenated solvents can be used in thecontext of the present invention, and are capable of dissolvingunsupported catalysts that are insoluble or only slightly soluble inhydrocarbon solvents, it is preferred to avoid using such solvents forenvironmental reasons. Naturally, if one is not concerned with thegeneration of volatile aromatics and/or halogen-containing components,or if one devises a mechanism to dispose (or reduce them to non-toxiccomponents) of them safely, then these solvents can be used. Mostpreferably, a solvent that is compatible with the particular solventthat is used is the solvent used to solvate the cocatalyst. In the caseof MMAO, this particular co-catalyst is available from Akzo-NobelChemicals, Inc. as a 1.91 Molar solution in heptane, 7.2 wt. % aluminum,and when used as the co-catalyst, it is preferred that a solvent that iscompatible with heptane (heptane, hexane, isopentane, etc.) is used asthe solvent.

[0107] Additional solvents typically are added to the mixture of theunsupported catalyst and the co-catalyst to reduce the concentration ofthe preactivated unsupported catalyst. Any additional solvent can beused in the context of the present invention. Again, aromatic and/orhalogen-containing solvents can be used, but it is preferred to avoidthe use of these solvents for environmental reasons. Preferably, theadditional solvent is an aliphatic or alicyclic hydrocarbon solvent,more preferably, the additional solvent is selected from butane,isobutane, ethane, propane, pentane, isopentane, hexane, heptane,octane, decane, dodecane, hexadecane, octadecane, and most preferably,the additional solvent is isopentane, hexane or heptane.

[0108] The size of the droplets formed when introducing the catalystsystem into the reactor is generally determined by the manner and placein which the catalyst is introduced. It is desirable to use a means ofintroduction which is able to provide liquid droplets in the reactorhaving an average diameter which is in the range of from about 0.1 toabout 1000 microns, preferably within a range of 0.1 to 500 microns,most preferably ranging from about 1 to 150 microns. A narrowdistribution of droplet size in a lower or mid range of about 10 toabout 100 microns can prevent the formation of large agglomeratesresulting from large droplets and the formation of fines resulting fromsmall droplets. Under many conditions, however, a wide droplet sizedistribution is acceptable as the smaller droplets can agglomerate tosome degree with the resin in the reactor and large droplets can formlarger particles of up to 0.25 which can be readily fluidized as long asthe particle fraction is low enough, preferably less than 10% and morepreferably less than 2% by weight of the total resin in the bed.

[0109] The catalyst in liquid form may be introduced into the reactionzone by simply passing the catalyst, under the impetus of pressure,through a conduit extending into the reactor, which may be assisted byan inert gas (such as nitrogen) and/or an inert liquid (such asisopentane, propane, and the like) to aid in atomization so as toprovide the desired liquid droplet size. The catalyst in liquid form maybe introduced by conventional means such as, for example, using positivedisplacement pumps, pressurizing the holding tank with an inert gas, andthe like. The extent of pressurization, the diameter of the conduit, thetype and size of atomization nozzle (if one is used), the velocity withwhich the catalyst is introduced into the reactor, the superficial gasvelocity of the fluids within the reactor, as well as the pressurewithin the reaction zone will all influence the liquid droplet size thatis formed. Using the guidelines provided herein, those skilled in theart are capable of varying one or more of these parameters to the extentdesired while adjusting others to obtain a desired droplet size withinthe reaction zone.

[0110] Generally, the catalyst in liquid form is introduced into thereactor by means of a conventional two fluid spray nozzle in which aninert gas is used to help atomize the catalyst. The use of such a spraynozzle allows for greater control of the liquid droplet size that isproduced in the reaction zone by providing enhanced atomizationcapability. The selection of a particular spray nozzle/tip for use withthe catalyst in liquid form to provide a desired average droplet size,taking into account the reaction conditions within the reactor as wellas the flow rate of the catalyst, is within the knowledge of thoseskilled in the art. Generally, the orifice diameter in the spraynozzle/tip is in the range of from about 0.01 to about 0.15 inch,preferably from about 0.02 to about 0.05 inch.

[0111] The average particle size of the polyolefin produced in thepresence of the preactivated unsupported catalyst can be controlled byadjusting the size of the liquid droplets containing preactivatedunsupported catalyst, or the concentration of preactivated unsupportedcatalyst in the liquid droplets, or both. If both the size of the liquiddroplets and the preactivated unsupported catalyst concentration in theliquid droplets are adjusted, they may be adjusted simultaneously or insequence.

[0112] The nature of both the unsupported catalyst and the activatingcocatalyst determine the magnitude and direction in which the size ofthe liquid droplets and the preactivated unsupported catalystconcentration in the liquid droplets should be adjusted in order toachieve a given average polyolefin product particle size. Typically, fora catalyst system comprising unsupported metallocene catalyst and liquidaluminoxane cocatalyst in a solvent (or solvent mixture) having a givendensity, used to produce an ethylene copolymer without severeagglomeration, the average particle size of the ethylene copolymer maybe increased or decreased by about 10% by adjusting the size of theliquid droplets by about 10% or adjusting the preactivated unsupportedcatalyst concentration in the liquid droplets (i.e., in the total liquidfeedstream of unsupported catalyst, cocatalyst, solvent(s), etc.) byabout 33%. Preferably, the average particle size of an ethylenecopolymer so made may be increased or decreased by about 20% byadjusting the size of the liquid droplets by about 20% or adjusting thepreactivated unsupported catalyst concentration by about 40%. Forconditions where an increase in liquid droplet size leads to anincreased rate of particle agglomeration, a 10% increase in liquiddroplet size can lead to a 50% or more increase in ethylene copolymeraverage particle size. Under such conditions, diluting the catalyst inthe liquid feedstream by 33% can decrease the ethylene copolymer averageparticle size by 50% or more. The same polyolefin size control achievedabove with respect to ethylene (co)polymers can also be achieved forpropylene (co)polymers.

[0113] The average diameter of the liquid droplets is generally in therange of about 0.1 to about 1000 micrometers, preferably 1 to 300micrometers, most preferably about 10 to 75 micrometers.

[0114] The size, i.e., average diameter, of the liquid droplets may beadjusted in one of several ways. For example, the flow rate of theliquid feedstream of preactivated unsupported catalyst, cocatalyst,solvent(s), etc. may be increased in order to increase the size of theliquid droplets, or decreased to decrease the size of the liquiddroplets. Alternatively, when the liquid droplets of unsupportedcatalyst are introduced into the reactor with the aid of an inertcarrier gas such as nitrogen, argon, alkane, or mixtures thereof, theflow rate of the inert carrier gas into the polymerization reactor maybe increased to break up the liquid into smaller sized droplets, whichin turn decreases the average particle size of the polyolefin produced.Alternatively, the flow rate of the inert carrier gas may be decreased,allowing the size of the liquid droplets to increase, thereby increasingthe average particle size of the polyolefin produced. This is apreferred method of adjusting the liquid droplet size, and therebypolyolefin average particle size.

[0115] The size of the liquid droplets containing the preactivatedunsupported catalyst can be adjusted while using an effervescent spraynozzle, such as that described in copending U.S. application Ser. No.08/802,231 for “Improved Control of Solution Catalyst Droplet Size withan Effervescent Spray Nozzle” of Williams, et al. (the disclosure ofwhich is incorporated by reference herein in its entirety) to spray theliquid feedstream containing the unsupported catalyst into thepolymerization reactor. In such an effervescent nozzle, a stream ofliquid or gas is passed through an inner tube, while a liquid or gas ispassed cocurrently through an annular space defined by the inner tubeand a concentric outer tube. The direction of flow of the liquid and gasis generally along the central axis of the tubes. The liquid feedstreamcontaining the unsupported catalyst and atomization gas are fed throughtheir respective inlets and exit through a common orifice at the spraytip. Towards the tip of the inner tube, though not necessarily at theend, there are holes (orifices) which allow the gas to enter the liquid.The gas is introduced into the cocurrent flowing liquid near the commonexit orifice. In this way, liquid slugging is prevented and steadydroplet formation occurs. Gas bubbles which are formed are forcedthrough an orifice at the tip of the outer tube, forcing the concurrentflow of liquid along the outside edge of the orifice. The thin film ofliquid on the orifice wall is ejected from the orifice in thin sheetswhich disintegrate into small droplets. The gas bubbles are thought torapidly increase in volume as they emerge form the orifice, providingadditional energy which shatters the liquid into small droplets. Using amathematical model, the size of the liquid droplets containing theunsupported catalyst sprayed from the effervescent nozzle can be readilycalculated and adjusted as desired.

[0116] The size of the liquid droplets containing the catalyst also canbe adjusted while using a perpendicular spray nozzle such as thatdescribed in copending U.S. application Ser. No. 08/803,230 entitled“Improved Control of Solution Catalyst Droplet Size with a PerpendicularSpray Nozzle” of Williams, et al. (the disclosure of which isincorporated by reference herein in its entirety), to spray the liquidcontaining the unsupported catalyst into the polymerization reactor.Such a perpendicular nozzle comprises a tube for delivering the liquidfeedstream containing the preactivated unsupported catalyst whereinthere is an inlet end for the input of the liquid, and optionally, agas. The other end of the tube (i.e., “distal end”) wherein there is atleast one exit hole (orifice) which is at least 10-20°, preferably morethan 45°, and most preferably 60 to 90°, off from the direction of flowof the liquid within the nozzle (i.e., from the central axis of thetube), where the orifice is located towards the distal end of thenozzle. Said nozzle may have any number of orifices and may include agas stream within the liquid feedstream. There is no need for a separatemixing chamber for the gas and liquid within the nozzle.

[0117] The distal end of the nozzle may be of any geometricconfiguration, e.g., bulbous, rounded, parabolic, conical, orsemi-circular, but to limit turbulence the nozzle preferably is taperedat about 5 to 15 degrees off horizontal (the central axis of the tube).Higher taper angles can be tolerated given that the taper fromhorizontal is gradual. A tapered tip also minimizes fouling because ofthe small area available for accumulation of catalyst and polymer.

[0118] For perpendicular spraying, the liquid feedstream may be atomizedwith an inert carrier gas, as is done with a gas-assisted perpendicularspray nozzle. Alternately, a perpendicular pressure nozzle could be usedto deliver a perpendicular spray of high-pressure liquid in the absenceof an atomizing gas. Additionally, the perpendicular feeding geometrycan be used with effervescent gas-liquid contact in the spraying nozzleor with an ultrasonic nozzle, or could also be applied to other knownatomization devices, such as electrostatic, sonic-whistle, or rotary,etc. nozzles.

[0119] Preferably, the preactivated unsupported catalyst in liquid formis introduced intermittently or continuously into the reaction zone at adesired point above the distributor plate. Intermittent catalyst feedingmay be used to help keep the catalyst solution flow rate in the properrange for optimum nozzle performance while independently maintaining thedesired average catalyst feed rate. It is desirable to maintain acontinuous flow of the inert carrier through the nozzle, be it a liquidor gas, at a rate sufficient to prevent fouling of the injection nozzle.Conventional metering valves or pumps can be used to deliver a preciseflow of the catalyst to the reaction zone. Controlled intermittentcatalyst flow may be delivered to the reaction zone using conventionalsyringe or positive displacement pumps.

[0120] Most preferably, the liquid preactivated unsupported catalyst isfed to the reactor in a “resin lean particle zone,” as described in U.S.Pat. No. 5,693,727. A resin particle lean zone can be established in thereactor by feeding the liquid preactivated unsupported catalyst in anymanner such that the catalyst droplets do not immediately contact asubstantial portion of the resin particles of the fluidized bed. Thedroplets of the preactivated unsupported catalyst in liquid form areintroduced without immediately contacting growing polymer particles ofthe bed so as to provide an average polymer particle size (APS) rangingfrom about 0.01 to about 0.06 inches. Generally, the particle density inthe particle lean zone is at least 10 times lower than that in thefluidized bed.

[0121] As disclosed in U.S. Pat. No. 5,317,036, a liquid, unsupportedcatalyst is typically dispersed in a solvent such as isopentane andintroduced into the fluidized bed using an inert carrier gas such asnitrogen. In the time period elapsing between when the liquid catalystin droplet form leaves the nozzle and when the liquid catalyst contactsthe particles in the bed, new polymer particles are formed. In thepresent invention, the time between the droplet leaving the nozzle andits contacting the particles in the bed ranges from about 0.01 secondsto 60 seconds, preferably about 0.01 to 30 seconds, and, mostpreferably, is about 0.01 seconds to 5 seconds.

[0122] A particle lean zone may be a section of the reactor whichnormally does not contain the fluidized bed, such as the disengagingsection, the gas recirculation system, or the area below the distributorplate. The particle lean zone may also be created by deflecting resinaway from the catalyst spray with a stream of gas.

[0123] In a preferred embodiment of the present invention, the liquidpreactivated unsupported catalyst is present in a carrier gas (e.g.,nitrogen, argon, other inert gases, alkane, or mixtures thereof), and issurrounded by at least one gas which serves to move or deflect resinparticles of the bed out of the path of the liquid catalyst as it entersthe fluidization zone and away from the area of catalyst entry, therebyproviding a particle lean zone. In a particularly preferred embodiment,the liquid preactivated unsupported catalyst in the carrier gas issurrounded by at least two gases, the first gas serving primarily todeflect resin particles of the bed out of the path of the liquidcatalyst and the second gas primarily prevents the injection tube ornozzle tip from getting clogged. As used throughout this description,when the liquid preactivated unsupported catalyst in the carrier gas issurrounded by two gases, the catalyst is considered to be shrouded. Thefirst or particle-deflecting gas and the second or tip-cleaning gas caneach be selected from the group consisting to recycle gas, monomer gas,chain transfer gas (e.g., hydrogen), inert gas or mixtures thereof.Preferably the particle-deflecting gas is all or a portion of therecycle gas and the tip-cleaning gas is all or a portion of a monomer(e.g., ethylene or propylene) employed in the process.

[0124] Liquid preactivated unsupported catalyst in a carrier gas,particle-deflecting gas, and, when employed, the tip-cleaning gas can beintroduced into the reactor at the same velocities to establish aparticle lean zone. However, it is preferred that they enter thefluidization zone at differing velocities. Preferably, the liquidpreactivated unsupported catalyst in the carrier gas is introduced at avelocity ranging from about 50 ft/sec to about 500 ft/sec; theparticle-deflecting gas is introduced at a velocity ranging from about10 ft/sec to about 280 ft/sec, and, when employed, the tip-cleaning gasranges in velocity from about 50 ft/sec to about 250 ft/sec. Preferably,the pressure of the particle-deflecting gas, and, when employed, thetip-cleaning gas is about 10 to about 300 psig, preferably about 20 toabout 200 psig, higher than the pressure of the gas in the fluidizationzone of the reactor. Typically, the particle-deflecting gas pressureranges from about 50 to about 600 psig; the tip-cleaning gas pressure,when employed, ranges from about 50 to 600 psig; and the liquidcatalyst/carrier gas pressure ranges from about 50 to about 600 psig.When the particle-deflecting gas is the recycle gas, it is a portioncomprising about 5 to about 40 percent of the total recycle flow and ispreferably removed from the discharge side of the compressor. When thetip-cleaning gas is the monomer gas, it is a portion comprising about 2to about 40 percent of the total monomer flow. The particle-deflectinggas and the tip-cleaning gas can also optionally contain one or moreantifoulants or antistatic agents known to those skilled in the art.While inert gases can be employed in the present invention as theparticle-deflecting and tip-cleaning gases, they can be impracticalbecause they require increased reactor venting, thereby decreasingefficiency of monomer usage and increasing cost.

[0125] Preactivated unsupported liquid catalyst can be introduced intothe polymerization zone from the side, top, or bottom of the reactor.Side feeding the liquid catalyst is generally preferred, since itrequires no or little modification of a conventional commercial reactor.When the liquid preactivated unsupported catalyst is fed from a sidelocation into the fluidization or polymerization zone of the reactor,it, along with the particle-deflecting gas and optional tip-cleaninggas, preferably enters the bed from a position that is about 10 percentto about 40 percent of the distance from the distributor plate to thetop of the bed, most preferably about 15 percent to about 25 percent ofthe distance from the distributor plate to the top of the bed. When theliquid, preactivated unsupported catalyst is fed from the bottom of thereactor along with the particle-deflecting gas and optional tip-cleaninggas, it preferably enters the fluidized bed from a position that is ator near the center of the distributor plate in the bottom of the reactorto provide a particle lean zone. When the liquid preactivatedunsupported catalyst is introduced from a location in the top of thereactor, it is preferred that it enter in such a manner so as to avoidpolymerization in the expanded zone of the reactor, and, therefore, isreleased in the reactor at the top or just immediately above thefluidized bed. This allows the catalyst droplets to additionally coatfines which can accumulate as dust above the top of the fluidized bed.

[0126] Any catalyst delivery system that is capable of atomizing theliquid catalyst into droplets of the desired size and distribution andavoids plugging of the tip or nozzle can be employed in the presentinvention. One embodiment of a catalyst delivery system comprises aparticle-deflecting gas tube enclosing an optional tip-cleaning gas tubewhich in turn encloses a catalyst injection tube. Theparticle-deflecting gas tube has a sufficient inside diameter for theinsertion or mounting of the tip-cleaning gas tube. For a commercialfluidized bed reactor, typically the particle-deflecting gas tube has aninside diameter ranging from about 2 inches to about 12 inches,preferably about 4 to about 6 inches. The optional tip-cleaning gastube, has an outside diameter capable of fitting inside theparticle-deflecting gas tube. For a conventional reactor, typically thetip-cleaning gas tube has an inside diameter ranging from about 0.5inches to about 1.5 inches, preferably about 0.75 to about 1.25 inches.

[0127] The particle-deflecting gas tube can be flush with the insidewall of the reactor or lead edge (top surface) of the distributor plate,or, preferably, it can be extended beyond the inside wall of the reactoror lead edge of the distributor plate into the fluidization zone.Preferably the particle-deflecting gas tube is flush with the insidewall or top of the distributor plate. When employed, the tip-cleaninggas tube can be positioned flush with, extended beyond, or recessed inthe particle-deflecting gas tube. Preferably the tip-cleaning gas tubeis flush with or recessed in the particle-deflecting gas tube. Mostpreferably the tip-cleaning gas tube is flush with theparticle-deflecting gas tube.

[0128] The catalyst injection tube or nozzle can be housed within theparticle-deflecting gas tube, but is preferably housed within thetip-cleaning gas tube which is inside the particle-deflecting gas tube.Preferably the catalyst injection tube or nozzle is tapered at its tipto a fine or knife edge to minimize surface area for injector foulingand convenient entry to the reactor vessel. The catalyst injection tubeor nozzle is secured or anchored to the inner wall of theparticle-deflecting gas tube or preferably to the tip-cleaning gas tubeby means of one or more fins or flanges. Stainless steel injectiontubing and pneumatic spray nozzles are commercially available in a widerange of internal diameters and thicknesses such that tubing or nozzlesize can easily be matched to the amount of catalyst solution feed. Fora commercial-size fluidized bed reactor, tubing and nozzles having abouta ⅛-inch inside diameter are employed. The orifice diameter in the spraynozzle tip is in the range of from about 0.01 inch to about 0.25 inch,preferably from about 0.02 inch to about 0.15 inch. The orifice diameterof the tip of the injection tube is between about 0.05 inch to about0.25 inches, preferably between about 0.1 inch to about 0.2 inches.Suitable nozzles can be obtained from Spraying Systems Corporation(Wheaton, Ill.) and can include the ⅛ JJ Series having standard andcustomized configurations. For a given liquid preactivated unsupportedcatalyst and reactor polymerization conditions, the catalyst liquid feedrates and the carrier gas and optional tip-cleaning gas feed rates canbe adjusted by one skilled in the art to obtain the desired droplet sizeand distribution, using the guidelines provided herein. The catalystinjection tube or nozzle can be located flush, extended, or recessedwith respect to the leading tip edge of the particle-deflecting gas tubeand/or optional tip-cleaning gas tube.

[0129] In the absence of the tip-cleaning gas tube, the catalystinjection tube or nozzle can be located flush, extended, or recessedwith respect to the leading tip edge of the particle-deflecting gastube. Preferably the catalyst injection tube or nozzle is located flushor extended with respect to the leading tip edge of theparticle-deflecting gas tube in the absence of the tip-cleaning gastube. Most preferably it is located flush in the particle-deflecting gastube. When a tip-cleaning gas tube is employed in conjunction with theparticle-deflecting gas tube, the catalyst injection tube or nozzle isextended beyond the leading edge of the tip-cleaning gas tube or flushwith the leading edge to the tip-cleaning gas tube. Preferably, thecatalyst injection tube or nozzle is extended 2 to 4 inches beyond theleading edge of the tip-cleaning gas tube, but recessed with respect tothe particle-deflecting gas tube.

[0130] The liquid preactivated unsupported catalysts of the presentinvention are preferably prepared by contacting the unsupported catalystwith a co-catalyst, or co-activator for a period of time sufficient topreactivate the catalyst. Simply contacting the two components in a feedline with a residence time of up to about 10 minutes, or contacting thecomponents in a mixing tee, or in a holding tank prior to adding thesolution to a gas phase reactor is not sufficient. Rather, thecomponents need to be in contact with one another for a period of timesufficient to preactivate the unsupported catalyst. For example, SIZR4Pand MMAO are known to be an effective unsupported catalyst/co-catalystsystem for polymerizing olefin monomers. It also is known that SIZR4P iseither insoluble, or only slightly soluble in hydrocarbon and,consequently, it typically is dissolved in toluene or methylenechloride. Even in methylene chloride, the solubility of SIZR4P is lessthan 21 mmol/l at room temperature. When SIZR4P and MMAO are contactedwith one another in the presence of hydrocarbon, like heptane, theinitial solution is yellow to yellow-orange. After sufficient contacttime has passed, typically more than 10 minutes, preferably more than 20minutes, and most preferably, more than 30 minutes, the solution turnsorange-red to deep red.

[0131] Other methods can be used to determine the time sufficient topreactivate the unsupported catalyst. The two components can becontacted until all of unsupported catalyst has substantially orcompletely dissolved in the reaction medium. Determining when theunsupported catalyst is dissolved in the hydrocarbon can be effectedvisually, or using other visual indicators known in the art. Further,the two components can be contacted with one another for more than twohours.

[0132] The unsupported catalyst component and the co-catalyst can becontacted with one another in any vessel, and at any temperature andpressure, so long as a preactivated unsupported catalyst is formed.Preferably, the two components are initially contacted at temperatureswithin the range of from −20° C. to about 50° C., more preferably, fromabout −10° C. to about 40° C., even more preferably from about 0-20° C.,and most preferably 10-30° C. The pressure before mixing is typicallyatmospheric to 50 psi, and preferably 15-25 psi.

[0133] In accordance with the present invention, the components areadded to the catalyst reaction vessel in the following order. Theco-catalyst first is added to the preactivation vessel, or reactionvessel, prior to addition of the unsupported catalyst. The co-catalystusually is added as a diluted solution in a hydrocarbon, for example, asa 5-10 wt % aluminum solution of MAO or MMAO in isopentane or heptane.

[0134] The unsupported catalyst then is added, preferably as a solidsince it is insoluble or only slightly soluble in hydrocarbon solvent,and the components permitted to react with one another. Additionalsolvent (preferably an aliphatic or alicyclic hydrocarbon solvent) thenis added to help dissolve or dilute the components and assist in feedingthe preactivated catalyst solution to the gas phase reactor. Thesolvent, unsupported catalyst and co-catalyst are added in such a mannerthat produces a preactivated unsupported catalyst whereby the ratio ofthe aluminum in the co-catalyst to the metal in the unsupported catalystpreferably is within the range of from about 20:1 to about 1500:1. Morepreferably, the ratio is within the range of from about 900:1 to about1200:1, and most preferably, the ratio is greater than about 950:1 andless than about 1100:1.

[0135] When the components have reacted for a sufficient period of timeto produce a preactivated unsupported catalyst, this preactivatedunsupported catalyst may be added directly to the gas phase reactor inthe form of a slurry or solution. Alternatively, the preactivatedunsupported catalyst may be separated from the solution bycrystallization, precipitation, filtration, drying, and the like to forma solid catalyst component that can be stored. Of course, thepreactivated unsupported catalyst also can be stored in slurry orsolution.

[0136] The preactivated unsupported catalyst of the invention can be feddirectly to a gas phase polymerization reactor, can be stored insolution or slurry, or can be separated from the solution or slurry andstored. It is preferred to add the preactivated unsupported catalystdirectly to the gas phase polymerization reactor. It also is preferredto pass the preactivated unsupported catalyst slurry or solution througha filter to filter out any residual solids and/or any non-preactivatedunsupported catalyst that may be suspended in the mixture. Mostpreferably the, preactivated unsupported catalyst solution is passedthrough a filter having a pore size ranging from about 0.01 to about 50microns, preferably from about 0.1 to about 20 microns, and morepreferably from about 0.5 to about 10 microns. Any filtering medium canbe used so long as it is capable of filtering residual solids and/or anynon-preactivated unsupported catalyst from the preactivated unsupportedcatalyst solution. Most preferably, a one micron polypropylene bagfilter is used.

[0137] In accordance with an additional preferred method of theinvention, the reaction vessel used to form the preactivated unsupportedcatalyst solution is subjected to a co-catalyst passivation step priorto contacting the components. Use of such a co-catalyst passivation isbelieved to reduce the presence of impurities in the reaction vessel.Co-catalyst passivation can be accomplished by adding the cocatalyst tothe vessel and letting it circulate for 2 minutes up to 2 hours,preferably at least 5 minutes. After circulation, the system can bepurged, preferably with N₂, although other inert materials may be used.After purging is complete, mixing of the cocatalyst and catalyst maycommence.

[0138] In accordance with the present invention, unsupported olefinpolymerization catalysts can be fed to a gas phase reactor in slurry orsolution by forming a preactivated unsupported catalyst. Thepreactivated unsupported catalysts are prepared by first reacting theunsupported catalyst precursor and co-catalyst, and then addingadditional solvent. If the unsupported catalyst precursors are added toa solution of co-catalyst and additional solvent (with our without evenmore solvent added after addition of the unsupported catalystprecursors), then the catalyst injection tube has a tendency to plug,even though the concentrations of the preactivated unsupported catalystsolutions are about the same. The preactivated unsupported catalystsalso are even more readily dissolved in aromatic and halogenatedsolvents, like toluene and methylene chloride. Thus, if these solventsare used as the additional solvent, even less liquid can be fed to thereactor and a more concentrated (concentrated with preactivatedunsupported catalyst) solution can be fed without causing plugging,reactor fouling, and the formation of catalyst balls. The presentinvention provides a highly active unsupported catalyst that is easy toprepare, does not leave undesirable reaction products in the resultingpolymer product, reduces reactor fouling, and reduces polymeragglomeration (or formation of catalyst balls) and injection tubeplugging. The present invention also provides a method of polymerizingolefin monomers in the gas phase to produce polymers in high yield, andhaving an excellent balance of properties.

[0139] While the invention has been described in detail with referenceto particularly preferred embodiments, those skilled in the art willappreciate that various modifications can be made without departing fromthe spirit and scope thereof. All documents described above areincorporated by reference herein in their entirety.

[0140] The following non-limiting examples will illustrate the inventionmore clearly, but are not intended to limit the present invention.

EXAMPLES Example 1

[0141] A number of samples were prepared whereby SIZR4P was used as theunsupported catalyst precursor. SIZR4P is represented by the following:

[0142] Numerous samples were prepared by contacting the unsupportedcatalyst precursor, SIZR4P with modified methylaluminoxane, MMAO, (type3A, 7.1 wt % Al in heptane, commercially available from Akzo-NobelChemicals, Inc.), and in all instances except sample 17, with additionalisopentane (iC5) in various orders. In sample 17, toluene was usedinstead of isopentane. In each of the samples, the SIZR4P was contactedwith MMAO in the presence of solvent (in the amount shown as initialconcentration) for at least 50 minutes. The amount of solvent added, theinitial concentration and final concentration of preactivatedunsupported olefin polymerization catalyst are shown in Table 1.

[0143] After preparing the preactivated unsupported catalystcomposition, additional solvent then was added (except in sample 17where no additional toluene was added) to bring the composition to itsfinal concentration, and the compositions were fed to a gas phasepolymerization reactor via a catalyst injection tube and nozzle havingthe following dimensions. The catalyst injection tube was standard{fraction (3/16)}″ stainless steel tubing, with a wall thickness of0.035 inches. The length of the tube from the catalyst slurry vessel,where the solution was stored to the reactor was approximately 10-25feet. The nozzle was a tapered tip made from ⅛ inch tubing where theinside diameter was decreased to 0.041 inches in diameter.

[0144] The following criteria were used to evaluate whether the catalystinjection tube and/or nozzle became plugged during polymerization. Astopping in catalyst flow was indicated by an increase in pressure ofthe catalyst injection line of 5 psig or more for more than 5 minutes.In addition, the valve position of the catalyst carriers (isopentane andnitrogen in this case) was monitored. If the motor valve whichcontrolled these materials needed to be opened further to maintain flowrate, this was also a sign of plugging. If either of these conditionsoccurred, then there would be a “yes” in the tube plugging column in thetable below. To determine whether discrete particles are formed and thatthe concentration of the preactivated unsupported catalyst is not toolow, the resin particle size was measured by sieving the resin. If resinfines were present in the resin (fines are defined as resin particleshaving an average particle size below 125 microns), this indicated thatthe solution concentration was high enough to prevent coating of resinparticles that results in runaway particle growth. The table belowindicates whether the catalyst injection tube was plugged (yes or no)and whether fines were generated (yes or no). TABLE 1 With Catalyst N2Initial IC5 Resin Feed Isopentane Flow Conc new Tube Fines Sample(cc/hr) (lb/hr) (lb/hr) mmol/l Conc plugs ? 1 55 1 7.4 0.787 0.058 noyes 2 75 1.5 7.5 0.808 0.055 no yes 3 100 1.5 7.9 0.808 0.071 no yes 480 2.1 6.9 0.789 0.041 no no 5 120 2.2 8 0.789 0.058 yes no 6 60 2.1 80.792 0.032 yes no 7 60 0.75 6 0.85 0.074 yes yes 8 200 1.97 6.5 0.850.1052 yes yes 9 70 1.91 7.13 0.791 0.040 yes yes 10 80 2 6 0.789 0.043no yes 11 120 2 6.7 0.646 0.052 yes no 12 120 2 6.7 0.646 0.052 yes no13 100 2.1 8.6 0.647 0.042 no no 14 110 3 6 0.647 0.033 no no 15 110 3 70.673 0.034 no no 16 150 5.7 7 0.650 0.024 no no 17 35 0 5.5 0.699 0.699no yes

[0145] As can be seen from Table 1, when an aliphatic solvent likeisopentane is used, the concentration of the preactivated unsupportedcatalyst preferably is above 0.04 to not only result in preventingplugging of the injection tube, but also to prevent the agglomerationand aggregation of polymer resin. In addition, when an aromatic solventlike toluene is used, additional solvent need not be added, and theconcentration of the preactivated unsupported catalyst can be muchhigher, on the order of about 0.8 mmol/liter or less to provide the sameeffect.

What is claimed is:
 1. A preactivated unsupported olefin polymerizationcatalyst composition comprising a preactivated unsupported olefinpolymerization catalyst and a solvent, wherein the preactivatedunsupported catalyst is prepared by contacting an unsupported olefinpolymerization catalyst precursor, a co-catalyst, and the solvent for aperiod of time sufficient to form a preactivated unsupported olefinpolymerization catalyst, wherein the solvent is selected from the groupconsisting of an aliphatic hydrocarbon solvent, an alicyclic hydrocarbonsolvent, an aromatic solvent, a halogen-substituted solvent, andmixtures thereof, and wherein the concentration of the preactivatedunsupported catalyst is within the range of from about 0.04 to about 0.1mmol of preactivated unsupported catalyst per liter of solution whenusing an aliphatic or alicyclic hydrocarbon solvent, and theconcentration is less than about 0.80 mmol/liter of preactivatedunsupported catalyst when using an aromatic or halogen-substitutedsolvent.
 2. The composition as claimed in claim 1 , wherein theunsupported olefin polymerization catalyst precursor is selected fromthe group consisting of racemic-dimethylsilylbis(2-methyl-1-indenyl)zirconium dichloride,racemic-dimethylsilylbis(2-methyl-4-(1-naphthyl)indenyl) zirconiumdichloride, and racemic-dimethylsilylbis(2-methyl-4-phenyl-1-indenyl)zirconium dichloride.
 3. The composition as claimed in claim 2 , whereinthe unsupported olefin polymerization catalyst precursor isracemic-dimethylsilylbis(2-methyl-4-phenyl-1-indenyl) zirconiumdichloride.
 4. The composition as claimed in claim 1 , whereinisopentane is used as the aliphatic or alicyclic solvent, and whereinthe preactivated unsupported olefin polymerization catalyst is presentin the composition in an amount of from about 0.045 to about 0.07 mmolper liter of solution.
 5. The composition as claimed in claim 1 ,wherein isopentane is used as the aliphatic or alicyclic solvent, andwherein the preactivated unsupported olefin polymerization catalyst ispresent in the composition in an amount of from about 0.048 to about0.07 mmol per liter of solution.
 6. The composition as claimed in claim2 , wherein the unsupported olefin polymerization catalyst precursor isracemic-dimethylsilylbis(2-methyl-1-indenyl) zirconium dichloride. 7.The composition as claimed in claim 2 , wherein the unsupported olefinpolymerization catalyst precursor isracemic-dimethylsilylbis(2-methyl-4-(1-naphthyl)indenyl) zirconiumdichloride.
 8. A method of making a polymer containing at least oneα-olefin comprising contacting an α-olefin monomer or monomers with acomposition according to claim 1 in a gas phase reactor.
 9. The methodas claimed in claim 8 , wherein the at least one α-olefin is propylene.10. A method of making the composition as claimed in claim 1 ,comprising contacting an unsupported olefin polymerization catalystprecursor, a co-catalyst, and a solvent selected from the groupconsisting of an aliphatic hydrocarbon solvent, an alicyclic hydrocarbonsolvent, an aromatic solvent, a halogen-substituted solvent, andmixtures thereof; optionally adding additional solvent selected from thegroup consisting of an aliphatic hydrocarbon solvent, an alicyclichydrocarbon solvent, an aromatic solvent, a halogen-substituted solvent,and mixtures thereof; and contacting the unsupported olefinpolymerization catalyst precursor, co-catalyst, solvent, and optionaladditional solvent for a period of time sufficient to form apreactivated unsupported olefin polymerization catalyst, wherein theconcentration of the preactivated unsupported olefin polymerizationcatalyst is within the range of from about 0.04 to about 0.1 mmol ofpreactivated unsupported catalyst per liter of solution when using analiphatic or alicyclic hydrocarbon solvent, and the concentration isless than about 0.80 mmol/liter of preactivated unsupported olefinpolymerization catalyst when using an aromatic or halogen-substitutedsolvent.
 11. The method as claimed in claim 10 , wherein the unsupportedolefin polymerization catalyst precursor is selected from the groupconsisting of racemic-dimethylsilylbis(2-methyl-1-indenyl) zirconiumdichloride, racemic-dimethylsilylbis(2-methyl-4-(1-naphthyl)indenyl)zirconium dichloride, andracemic-dimethylsilylbis(2-methyl-4-phenyl-1-indenyl) zirconiumdichloride.
 12. The method as claimed in claim 10 , wherein theunsupported olefin polymerization catalyst precursor isracemic-dimethylsilylbis(2-methyl-4-phenyl-1-indenyl) zirconiumdichloride.
 13. The method as claimed in claim 10 , wherein isopentaneis used as the aliphatic or alicyclic solvent, and wherein thepreactivated unsupported olefin polymerization catalyst is present inthe composition in an amount of from about 0.045 to about 0.07 mmol perliter of solution.
 14. The method as claimed in claim 10 , whereinisopentane is used as the aliphatic or alicyclic solvent, and whereinthe preactivated unsupported olefin polymerization catalyst is presentin the composition in an amount of from about 0.048 to about 0.07 mmolper liter of solution
 15. The method as claimed in claim 10 , whereinthe unsupported olefin polymerization catalyst precursor isracemic-dimethylsilylbis(2-methyl-1-indenyl) zirconium dichloride. 16.The method as claimed in claim 10 , wherein the unsupported olefinpolymerization catalyst precursor isracemic-dimethylsilylbis(2-methyl-4-(1-naphthyl)indenyl) zirconiumdichloride.
 17. A preactivated unsupported olefin polymerizationcatalyst composition comprising a preactivated unsupported olefinpolymerization catalyst, and a solvent, wherein the preactivatedunsupported catalyst is prepared by contacting an unsupported olefinpolymerization catalyst precursor, a co-catalyst, and the solvent formore than about 40 minutes, wherein the solvent is selected from thegroup consisting of an aliphatic hydrocarbon solvent, an alicyclichydrocarbon solvent, an aromatic solvent, a halogen-substituted solvent,and mixtures thereof, and wherein the concentration of the preactivatedunsupported catalyst is within the range of from about 0.04 to about 0.1mmol of preactivated unsupported catalyst per liter of solution whenusing an aliphatic or alicyclic hydrocarbon solvent, and theconcentration is less than about 0.80 mmol/liter of preactivatedunsupported catalyst when using an aromatic or halogen-substitutedsolvent.
 18. The composition as claimed in claim 17 , wherein theunsupported olefin polymerization catalyst precursor is selected fromthe group consisting of racemic-dimethylsilylbis(2-methyl-1-indenyl)zirconium dichloride,racemic-dimethylsilylbis(2-methyl-4-(1-naphthyl)indenyl) zirconiumdichloride, and racemic-dimethylsilylbis(2-methyl-4-phenyl-1-indenyl)zirconium dichloride.
 19. A method of making the composition as claimedin claim 1 , comprising contacting an unsupported olefin polymerizationcatalyst precursor, a co-catalyst, and a solvent selected from the groupconsisting of an aliphatic hydrocarbon solvent, an alicyclic hydrocarbonsolvent, an aromatic solvent, a halogen-substituted solvent, andmixtures thereof; optionally adding additional solvent selected from thegroup consisting of an aliphatic hydrocarbon solvent, an alicyclichydrocarbon solvent, an aromatic solvent, a halogen-substituted solvent,and mixtures thereof; and contacting the unsupported olefinpolymerization catalyst precursor, co-catalyst, solvent, and optionaladditional solvent for greater than about 40 minutes to form apreactivated unsupported olefin polymerization catalyst, wherein theconcentration of the preactivated unsupported olefin polymerizationcatalyst is within the range of from about 0.04 to about 0.1 mmol ofpreactivated unsupported catalyst per liter of solution when using analiphatic or alicyclic hydrocarbon solvent, and the concentration isless than about 0.80 mmol/liter of preactivated unsupported olefinpolymerization catalyst when using an aromatic or halogen-substitutedsolvent.
 20. The method as claimed in claim 19 , wherein the unsupportedolefin polymerization catalyst precursor is selected from the groupconsisting of racemic-dimethylsilylbis(2-methyl-1-indenyl) zirconiumdichloride, racemic-dimethylsilylbis(2-methyl-4-(1-naphthyl)indenyl)zirconium dichloride, andracemic-dimethylsilylbis(2-methyl-4-phenyl-1-indenyl) zirconiumdichloride.